Abstract: OBJECTIVE 1. To analyze the drug resistance profiles of different sequencing types (STs) of carbapenem-resistant Acinetobacter baumannii (CRAB) and observe the association with multilocus sequence typing (MLST). METHODS Totally 398 strains of clinical non-repetitive CRAB isolates were collected from Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine from Jul. 2022 to Dec. 2024. The antimicrobial susceptibility testing was carried out by Vitek-2 Compact system, MLST was performed based on Oxford program, and the drug resistance rates to 16 types of antibiotics were observed and compared among the various STs of CRAB. RESULTS A total of 9 STs were detected among the 398 strains of CRAB; ST208(38.69%), ST369(34.17%) and ST195(13.82%) were the predominant clones, accounting for 86.68% altogether. The different STs exhibited characteristic drug resistance profiles. The drug resistance rate of ST208 strains to cefoperazone-sulbactam was low (51.95%), the strains were highly sensitive to tigecycline (with the drug resistance rate 1.30%); the ST369 strains exhibited unique quinolones phenotype (with the intermediate rate to levofloxacin 38.97%). The drug resistance rate of the ST195 strains to sulfamethoxazole-trimethoprim was 61.82%, lower than 92.21% to 98.53% of other major clones. The ST784 strains were highly sensitive to amikacin (with the drug resistance rate 18.75%), and the strains were mainly intermediate to gentamycin(81.25%). The result of statistical analysis showed that there were significant differences in the associations of the drug resistance rates to the above drugs with MLST types(P＜0.05). CONCLUSIONS The prevalent clones of CRAB strains exhibit a relatively concentrated distribution in the hospital, and the STs are closely associated with the specific drug resistance phenotypes. MLST genotyping combined with drug resistance profiles facilitates the early identification of dominant clones and informs ‘remaining therapeutic options', offering significant clinical value in guiding the individualized treatment and precise prevention and control of CRAB infections.